1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) system, and more particularly, to an apparatus for driving a multi-synchronization type LCD panel for different size images.
2. Description of the Related Art
There has been known a multi-synchronization type deflecting apparatus for a cathode-ray tube (CRT) panel which can properly display images having different numbers of scan lines at a center portion of the panel. On the other hand, since LCD panels are thinner in size and lower in power consumption with a lower power supply voltage as compared with CRT panels, the LCD panels have recently been applied to personal computers, word processors, color telereceivers, and the like. However, the multi-synchronization type deflecting system of the CRT panels cannot be applied to the multi-synchronization type driving system of the LCD panels, due to the difference in driving (deflecting) methods therebetween.
In a prior art apparatus for driving an LCD panel having M signal lines, N scan lines and M.times.N liquid crystal cells connected to the signal lines and the scan lines, the operation of a signal line driving circuit for sequentially driving the signal lines is started by a horizontal start timing signal which is obtained by delaying a horizontal synchronization signal with a constant time period. Similarly, the operation of a scan line driving circuit for sequentially driving the scan lines is started by a vertical start timing signal which is obtained by delaying a vertical synchronization signal with a constant time period. As a result, an image having a size different from M.times.N dots is ill-balanced at an upper portion or a left portion of the LCD panel. This will be explained later in detail.